Co-Seismic Inversion and Post-Seismic Deformation Mechanism Analysis of 2019 California Earthquake

In July 2019, a series of seismic events, including a magnitude (Mw) 7.1 mainshock and Mw 6.4 foreshock, occurred in Eastern California. Studying these seismic events can significantly improve our understanding of the Eastern California tectonic environment. Sentinel-1A and ALOS-2 PALSAR images were utilized to obtain co-seismic deformation fields, including mainshock and foreshock deformation. The Okada elastic dislocation model and ascending and descending orbit results were used to invert the co-seismic slip distribution and obtain a co-seismic focal mechanism solution. Using ascending Sentinel-1A images, a time-series deformation was obtained for 402 d after the earthquake, and the deformation evolution mechanism was analyzed. The maximum uplift caused by the co-seismic mechanism reached 1.5 m in the line of sight (LOS), and the maximum subsidence reached 1 m in the LOS. For 402 d after the earthquake, the area remained active, and its deformation was dominated by after-slip. The co-seismic inversion results illustrated that California earthquakes were mainly strike-slip. The co-seismic inversion magnitude was approximately Mw 7.08. The Coulomb stress change illustrated that the seismic moment caused by the co-seismic slip was 4.24 x 10(26) N x m, which is approximately Mw 7.06. This finding is consistent with the co-seismic slip distribution inversion results.

Automated summary

By utilizing satellite images and modeling inversion, studying the deformation field and seismic source mechanism of seismic events in Eastern California, it was discovered that earthquakes in the region are mainly strike-slip, and the seismic moment caused by aftershock slip was 4.24 x 10(26) N x m, approximately equivalent to Mw 7.06. The deformation evolution is primarily influenced by afterslip.